1. Field of the Invention
The present invention relates to a power control method applied to mobile communication, and more particularly, to an uplink transmission power control method.
2. Discussion of the Related Art
Generally, uplink transmission power control in mobile communication system is essential to enhancement of system reception capacity and efficient terminal power use. An uplink transmission power control method according to a related art is explained as follows.
First of all, a base station receives an uplink transmission signal transmitted from a terminal, and decides whether to have the terminal raise/lower its uplink transmission power according to the transmitted signal. The base station then transmits a transmission power control command to the terminal according to the decision.
The terminal (UE; user equipment) receives the transmission power control commands transmitted from the base station (node-B), and determines the uplink transmission power according to the power control commands. The terminal then performs uplink transmission according to a result of the determination to accomplish the uplink transmission power control.
The uplink transmission power control method is explained in detail as follows.
Referring to FIG. 1, a terminal receives transmission power control commands transmitted from one base station. In case that the entire power control commands received for a predetermined continuous time slot indicate ‘transmission power increase’, the terminal decides to raise uplink transmission power.
Otherwise, if the entire transmission power control commands received for the predetermined continuous time slot indicate ‘transmission power decrease’, the terminal decides to lower the uplink transmission power.
Meanwhile, in case that the transmission power control commands received for several time slots indicate ‘transmission power increase’ and that another power control commands received for another several times slots indicate ‘transmission power decrease’, the terminal determines to maintain the transmission power. And, the terminal lowers, raises, or maintains the uplink transmission power according to a result of the determination. In uplink transmission power, a method of controlling transmission power by determining one of three states including increase/decrease/maintain is called a 3-states power control method.